Sefer Ha’mitzvos Ha’Katzar (the concise book of mitzvos)
By the Chofetz Chaim
This book lists the Torah mitzvos that can be observed today
First Section – the Positive Commandments
10. It is a positive commandment to make tzitzis on the corners of their clothes
As it says in Bamidbar (Numbers) 15:38, “And they shall make for them tzitzis on the corners of their clothes.” When it is clothing a man wears during the day; there are four corners or more; its size covers the head and body of a child that can walk alone in the street and does not need anyone to guard him; and it is a garment made of wool or linen, it is obligated in tzitzis from the Torah. But other kinds of material require tzitzis only according to the Rabbanan (Sages).
And if someone covers himself with a tallis that has four corners and does not have tzitzis on it, he disobeys a positive commandment. A youngster that knows how to wrap himself is obligated in tzitzis according to the Law of the Sages. A person needs to be very careful with the commandment of tzitzis because the Torah makes it equal to all of the commandments and attaching them to it as it says in Bamidbar (Numbers) 15:39, “And you shall see them and remember all of the commandments of Hashem.”
This commandment is obligatory in all places and at all times, for men but not for women.